*{
	box-sizing: border-box;
}
body{
	padding: 0;
	margin: 0;
	position: relative;
	background-color: rgba(100,255,200,.2);
}
.clearfix::after{
	content: "";
	clear: both;
	display: block;
}
ul{
	padding: 0;
	margin: 0;
}
/*header头部*/
   header{
	margin-top: 110px;
	background-color: rgba(0,0,0,.3);
	height: 45px;
	position: relative;
	/*margin-bottom: 40px;*/
	/*top: 50px;*/
}
header .nav {
	/*float: right;*/
	/*border: 1px solid #fff;*/
	width: 520px;
	height: 45px;
	position: absolute;
	top: 0;
	bottom: 0;
	left: 0;
	right: 0;
	margin: auto;
	list-style: none;
}

header .nav li {
	float: left;
	width: 105px;
	height: 100%;
	/*border: 1px solid #fff;*/
	text-align: center;
	margin-right: 20px;
}

header .nav li:last-child {
	margin-right: 0;
}

header .nav li a {
	/*font-size: 20px;*/
	color: #fff;
	text-decoration: none;
	font-weight: bold;
}

header .nav li:nth-child(2) a span {
	background-color: #fff;
	color: rgba(0, 0, 0, .5);
}

header .nav li a span {
	display: block;
	/*border: 1px solid #fff;*/
	height: 44px;
	padding-top: 10px;
	transition: color, background-color .5s;
}

header .nav li:hover span {
	color: rgba(0, 0, 0, .5);
	background-color: #fff;
}
/*主体部分*/
main{
	position: relative;
}
main .logo{
	position: absolute;
	left: 0;
	right: 0;
	margin: auto;
	/*border: 1px solid #000;*/
	width: 270px;
}
main .logo img{
	width: 100%;
	height: auto;
}
.case{
	/*border: 1px solid #000;*/
	width: 1000px;
	/*height: 2000px;*/
	position: absolute;
	top: 300px;
	left: 0;
	right: 0;
	margin: auto;
	list-style: none;
}
.case li{
	width: 400px;
	height: 322px;
	float: left;
	margin-bottom: 55px;
	cursor: pointer;
	/*border: 1px solid #000;*/
	overflow: hidden;
	
}
.case li:nth-child(2n){
	float:right;
}
/*.case li:nth-child(3){
	margin-bottom:0;
}
.case li:nth-child(4){
	margin-bottom:0;
}*/
.case li figure{
	width: 100%;
	height: 100%;
	margin:0;
	position: relative;
}
.case li figure img{
	width: 100%;
	height: 100%;
}
.case li figure figcaption{
	width: 400px;
	height: 322px;
	line-height: 285px;
	text-align: center;
	position: absolute;
	left: 0;
	right: 0;
	top: 0;
	bottom: 0;
	margin: auto;
}
.case li:hover figure figcaption{
	background-color: rgba(0,0,0,.2);
}
.case li figure figcaption a{
	color: transparent;
	font-size: 20px;
	/*text-shadow: 1px 1px 1px rgba(0,0,0,0);*/
	text-decoration: none;
	transition: color .5s; 
}
.case li:hover figure figcaption a{
	color: #fff;
	text-shadow: 1px 1px 1px rgba(0,0,0,.5);
}
footer{
	width: 100%;
	height: 100px;
	border-top: 1px solid rgba(0,0,0,.2);
	position: absolute;
	top: 1500px;
	margin: auto;
}
.footer{
	/*border: 1px solid #000;*/
	width: 100%;
	height: 100px;
	position: relative;
}
.footer .copyright{
	/*border: 1px solid #000;*/
	width: 410px;
	height: 50px;
	position: absolute;
	left: 0;
	right: 0;
	top: 0;
	bottom: 0;
	margin: auto;
}
.footer .copyright p{
	color: rgba(0,0,0,.5);
}